Reproductive Traits of Some Amphipods (Crustacea: Peracarida) in Different Habitats of Iran and Southern Caspian Sea
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Hindawi Publishing Corporation International Journal of Zoology Volume 2011, Article ID 598504, 10 pages doi:10.1155/2011/598504 Research Article Reproductive Traits of Some Amphipods (Crustacea: Peracarida) in Different Habitats of Iran and Southern Caspian Sea Alireza Mirzajani,1 Mostafa Sayadrahim,1 and Alireza Sari2 1 Department of Ecology, Inland Water Aquaculture Research Center, P.O. Box 66, 43167 Guilan, Iran 2 School of Biology, University College of Science, University of Tehran, 14155 Tehran, Iran Correspondence should be addressed to Alireza Mirzajani, ar [email protected] Received 20 December 2010; Revised 16 February 2011; Accepted 12 April 2011 Academic Editor: Chris Lloyd Mills Copyright © 2011 Alireza Mirzajani et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Reproductive traits of seven amphipods from northern parts of Iran at 11 localities were studied in order to find feasible species for usage in aquaculture industries. The results revealed that the breeding season for Gammarus lacustris and G. paricrenatus from high latitudes was limited to a few months from May to June. Breeding activity of G. komareki from some springs was observed throughout the year, while Obesogammarus acuminatus and G. aequicauda from southern wetlands of the Caspian Sea and Pontogammarus maeoticus and P. borceae from southern Caspian sea shore showed various patterns. The mean egg number of O. acuminatus and G. aequicauda species was the highest with 49.8 and 37.7, respectively, while this value for G. komareki and P. maeoticus was the lowest with an average of 8.8 eggs. Reproductive strategy was found to be related to habitat characteristics such as chemical factors, substrate status, and the epifaunal living. 1. Introduction of Nelson [3], Kolding and Fenchel [4], and Sainte-Marie [5] are informative about reproductive patterns. According to Amphipods are often selected as test organisms in different Sainte-Marie [5] life histories of gammarideans fall into eight studies because of their widespread distribution, sensitivity categories. Most of them are an iteroparous annual type; the to disturbance, and culture suitability [1]. Introduction of high reproductive potentials were described for semiannual macroinvertebrates such as crustacean to fish culture ponds populations in low latitude habitats while low reproductive has been used to improve fish diet, and many amphipods potentials were more frequent in perennial gammarideans at have been used [2]; others can be found in the website high latitudes. (http://www.elacuarista.com/). Amphipod adaptation and During a project [6] to find suitable species of amphipods continuous reproduction in the new environment are the for aquaculture industries, the reproductive traits of Am- main factors for success. phipoda were examined in different habitats from the north- A wide variation in reproductive parameters is found ern part of Iran. The selected species were Gammarus lacus- within amphipods, correlated with a wide variety of micro- tris G. O. Sars, 1863, G. paricrenatus Stock et al. 1998, G. habitat conditions. A wide variation in reproductive parame- komareki Schaferna,˜ 1992, G. aequicauda Martynov, 1931, ters is found within amphipods corresponding to diversity of Obesogammarus acuminatus Stock et al. 1998, Pontogam- microhabitats conditions. In this regard, many comparisons marus maeoticus (Sowinsky, 1894), and P. borceae (Carausu, of reproductive traits were explained by Nelson [3]forbrack- 1943) from Iranian inland waters and southwest coast of the ish water versus freshwater and marine, single-brooded ver- Caspian sea. All species had been confirmed previously by sus multiple-brooded, and infaunal versus epifaunal species. Stock et al. [7]. It was important to investigate their life cycle However, an extensive literature has been published on the and breeding season in their respective habitats as reproduc- biology and life cycles of different amphipods; the studies tive traits vary with local water environment parameters. 2 International Journal of Zoology has been described as a new species [7]. On the other hand no specimens of Obesogammarus acuminatus were found in Anzali Wetland for a few months. The sampling was conducted by an Ekman dredge for Caspian sea muddy substrate or by a handle sieve (0.125 mm screen) for the aquatic vegetation and sandy substrates. The animals were washed from debris and preserved in 75% alcohol. In the laboratory, the length of the animal was measured to the nearest 1 mm from the anterior head margin to the posterior Caspian sea margin of the telson with a stereomicroscope fitted with a H Astara graticule. Animals were classified into five groups. Sex deter- 38 N mination was according to the presence of oostegites. Breed- N Sefid Rud estuary ing periods, clutch sizes, and ovigerous females percentage determined the breeding activity during the year. Juveniles Kelachi in the brood pouch were assessed separately. The sex ratio S was calculated for adults (longer than eight mm), and the t K mean length of adults was compared for each sex using a - test. For multiple comparison of means ANOVAwas used for some data analysis. Some environment characteristics such 36 N 52 E 54 E as hydrochemical parameters were measured by standard 48 E 50 E methods [16] to show the habitats variation. Anzali Wetland Gorgan Bay 3. Results Neur Lake Gorigol Wetland Biometric results showed a significant difference between the Caspian sea shore mean length of males and females where in most species Spring (H: Hiran N: Navrud males were longer than females, although Pontogammarus S: Sefidab K: Kojor) maeoticus was larger than males (Table 2). The sex ratios were Figure 1: Sampling localities in northern parts of Iran. highly variable for all species during the year while in the adult stage the male dominated. In P. borceae the sex ratio was 1 : 1.1, 1 : 1.2 for G. paricrenatus, G. komareki, G. aequicauda, 2. Study Area and Methods O. acuminatus and 1 : 2.2 for P. maeoticus (Table 2). The length-frequency histogram (Figure 2)ofGammarus Different features of reproduction were studied in seven lacustris shows that newly hatched (<4 mm long) individuals Amphipoda species from 11 habitats in the northern part dominate with 43% and 23% of the population in June and of Iran (Table 1, Figure 1) mostly from the Caspian drainage July (Figure 3), respectively. They grow during the following basin. On the Iranian coast of the Caspian Sea Pontogam- months to juveniles with lengths of 4–8 mm, and their marus maeoticus is the most abundant and widely distributed frequency in the population was 38% to 65% during August [8], and P. borceae is much less abundant [9], both of which and October, respectively. The larger specimens (>12 mm) are considered in this study. Generally P. maeoticus inhabits constituted the highest abundance in April and May with the sublittoral region and is known from the Pontic and Azov 84% and 37%, respectively. The newly hatched (<4mmlong) Sea basins [10]whileP. borceae has already been identified individuals of G. paricrenatus (Figure 3) dominated in May– from the Pontic area with rheophilous characteristics [11]. July and comprised 30% to 49% of the population. They Gammarus komareki from small streams and springs is the grow during the following months as the juveniles (4–8mm most common freshwater gammarid [7, 12] in the northern long) make up 65% of the population during August. The part of Iran. It is also distributed in Bulgaria, the northern larger specimens (>12 mm) show the highest frequency of part of Greece and Turkey, and around the Black sea [12]. At 72% in March (Figure 2). The maximum mean length was the south east of the Caspian sea in Gorgan Bay the common observed in May and the minimum in June (Figure 4). Mediterranean species G. aequicauda introduced to Caspian Studies on G. aequicauda Martynov, 1931 (Figure 2) water before 1994 [13] is also considered. revealed that newly hatched (<4 mm long) individuals The specimens were collected monthly from April 2001 present all year round while the frequency of juvenile (4– to March 2002, though a few samples were missed in Neur 8 mm long) in the population was more than 50% (Figure 3). Lake and Gorigol Wetland due to heavy snow and ice The larger specimens (>12 mm) constituted only 20 to 30% coverage of the Lake. Stock et al. [7]reportedG. lacustris in of the population in most periods, and the largest specimen Neur Lake and many other sites, previously recorded from was 19 mm in length. Iran [14]. This species is widely distributed throughout the Length-frequency histograms of O. acuminatus revealed world and prefers mountain and glacier Lakes as habitats that newly hatched and juvenile (<8 mm long) individu- [12, 15]. In the Gorigol Wetland, Gammarus paricrenatus als were present in all sampling periods (Figure 3)when International Journal of Zoology 3 19 55 17 150 93 47 5 39 44 85 15 13 11 No specimens 9 7 5 3 1 17 134 134 32 15 50 200 137 42 104 18 133 88 13 143 11 9 7 5 3 1 20020200 20 30 0 3025525 5 10 0 10 30 0 30 255525 10 0 10 10 0 10 25552520 0 20 20 0 20 11 229 222 119 166 105 246 177 161 14 260 151 9 164 7 5 3 1 11 125 167 84 47 73 9 25 29 70 101 111 75 7 5 3 1 11 301 250 296 297 270 310 119 425 235 227 9 165 97 7 5 3 1 17 264 137 243 166 103 128 117 15 Without sampling 13 11 9 7 5 3 1 15 13 314 306 150 113 11 33 253 173 123 9 7 5 Without sampling 3 1 G.